[PATCH v11 0/5] iommu: Support mappings/reservations in reserved-memory regions

[PATCH v11 0/5] iommu: Support mappings/reservations in reserved-memory regions

[Thierry Reding]

From: Thierry Reding <treding@nvidia.com>

Hi,

This version has several fixes over the previous v10, which can be found
here:

  https://lore.kernel.org/all/20221103133900.1473855-1-thierry.reding@gmail.com/

Most notably this introduces a better mechanism to deal with DMA address
translation issues caused by a mismatch of #address-cells in child and
DMA parent nodes. This now introduces #dma-address-cells and #dma-size-
cells, which can be used to override #address-cells and #size-cells and
define a DMA bus that can be wider than the control bus.

An example is included in the DT bindings, but here is an extract of
what I've used to test this:

        reserved-memory {
                #address-cells = <2>;
                #size-cells = <2>;
                ranges;

                /*
                 * Creates an identity mapping for the framebuffer that
                 * the firmware has setup to scan out a bootsplash from.
                 */
                fb: framebuffer@92cb2000 {
                        reg = <0x0 0x92cb2000 0x0 0x00800000>;
                        iommu-addresses = <&dc0 0x0 0x92cb2000 0x0 0x00800000>;
                };

                /*
                 * Creates a reservation in the IOVA space to prevent
                 * any buffers from being mapped to that region. Note
                 * that on Tegra the range is actually quite different
                 * from this, but it would conflict with the display
                 * driver that I tested this against, so this is just
                 * a dummy region for testing.
                 */
                adsp: reservation-adsp {
                        iommu-addresses = <&dc0 0x0 0x90000000 0x0 0x00010000>;
                };
        };

        host1x@50000000 {
                dc@54200000 {
                        memory-region = <&fb>, <&adsp>;
                };
        };

This is abbreviated a little to focus on the essentials. Note also that
the ADSP reservation is not actually used on this device and the driver
for this doesn't exist yet, but I wanted to include this variant for
testing, because we'll want to use these bindings for the reservation
use-case as well at some point.

I've also been able to make use of this binding and the IOMMU code in
conjunction with the simple-framebuffer driver to hand over a display
configuration set up by UEFI to the Linux kernel.

Janne has confirmed[0] this to be suitable for indirect mappings as
well, though these patches don't implement that feature yet. Potential
extensions to this have been discussed but are not yet included at this
time to not further complicate things.

Thierry

[0]: https://lore.kernel.org/all/20220909144504.GA4024@jannau.net/



Thierry Reding (5):
  of: Introduce support for #dma-{address,size}-cells
  of: Introduce of_translate_dma_region()
  dt-bindings: reserved-memory: Document iommu-addresses
  iommu: Implement of_iommu_get_resv_regions()
  iommu: dma: Use of_iommu_get_resv_regions()

 .../reserved-memory/reserved-memory.yaml      | 73 ++++++++++++++
 drivers/iommu/dma-iommu.c                     |  3 +
 drivers/iommu/of_iommu.c                      | 94 +++++++++++++++++++
 drivers/of/address.c                          | 84 +++++++++++++----
 drivers/of/base.c                             | 70 +++++++++++---
 drivers/of/of_private.h                       | 14 ++-
 include/linux/of.h                            | 17 +++-
 include/linux/of_address.h                    |  4 +-
 include/linux/of_iommu.h                      |  8 ++
 9 files changed, 329 insertions(+), 38 deletions(-)

-- 
2.38.1

[PATCH v11 1/5] of: Introduce support for #dma-{address,size}-cells

[Thierry Reding]

From: Thierry Reding <treding@nvidia.com>

The control and DMA busses of a system can have differing addressing
requirements. One common case of this is SoCs with CPUs that can address
more than 32 bits of system memory, but for simplicity want to describe
the control busses using #address-cells = <1> and #size-cells = <1>. In
this case, DMA address translation will fail because > 32-bit addresses
will be truncated to 32-bit addresses.

Support for the new #dma-address-cells and #dma-size-cells properties is
introduced in this patch. If these are encountered, they will be used
instead of the #address-and #size-cells properties when translating DMA
addresses.

Signed-off-by: Thierry Reding <treding@nvidia.com>
---
Changes in v11:
- new patch

 drivers/of/address.c       | 43 ++++++++++++-----------
 drivers/of/base.c          | 70 ++++++++++++++++++++++++++++++--------
 drivers/of/of_private.h    | 14 ++++++--
 include/linux/of.h         | 17 +++++++--
 include/linux/of_address.h |  2 +-
 5 files changed, 108 insertions(+), 38 deletions(-)

diff --git a/drivers/of/address.c b/drivers/of/address.c
index c34ac33b7338..db59bc60226c 100644
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -45,8 +45,8 @@ struct of_bus {
 	const char	*name;
 	const char	*addresses;
 	int		(*match)(struct device_node *parent);
-	void		(*count_cells)(struct device_node *child,
-				       int *addrc, int *sizec);
+	void		(*count_cells)(struct device_node *child, int *addrc, int *sizec,
+				       unsigned int flags);
 	u64		(*map)(__be32 *addr, const __be32 *range,
 				int na, int ns, int pna);
 	int		(*translate)(__be32 *addr, u64 offset, int na);
@@ -58,13 +58,13 @@ struct of_bus {
  * Default translator (generic bus)
  */
 
-static void of_bus_default_count_cells(struct device_node *dev,
-				       int *addrc, int *sizec)
+static void of_bus_default_count_cells(struct device_node *dev, int *addrc, int *sizec,
+				       unsigned int flags)
 {
 	if (addrc)
-		*addrc = of_n_addr_cells(dev);
+		*addrc = of_addr_cells(dev, flags);
 	if (sizec)
-		*sizec = of_n_size_cells(dev);
+		*sizec = of_size_cells(dev, flags);
 }
 
 static u64 of_bus_default_map(__be32 *addr, const __be32 *range,
@@ -155,8 +155,8 @@ static int of_bus_pci_match(struct device_node *np)
 		of_node_is_pcie(np);
 }
 
-static void of_bus_pci_count_cells(struct device_node *np,
-				   int *addrc, int *sizec)
+static void of_bus_pci_count_cells(struct device_node *np, int *addrc, int *sizec,
+				   unsigned int flags)
 {
 	if (addrc)
 		*addrc = 3;
@@ -272,8 +272,8 @@ static int of_bus_isa_match(struct device_node *np)
 	return of_node_name_eq(np, "isa");
 }
 
-static void of_bus_isa_count_cells(struct device_node *child,
-				   int *addrc, int *sizec)
+static void of_bus_isa_count_cells(struct device_node *child, int *addrc, int *sizec,
+				   unsigned int flags)
 {
 	if (addrc)
 		*addrc = 2;
@@ -475,6 +475,7 @@ static u64 __of_translate_address(struct device_node *dev,
 				  const __be32 *in_addr, const char *rprop,
 				  struct device_node **host)
 {
+	unsigned int flags = (rprop && !strcmp(rprop, "dma-ranges")) ? OF_CELLS_DMA : 0;
 	struct device_node *parent = NULL;
 	struct of_bus *bus, *pbus;
 	__be32 addr[OF_MAX_ADDR_CELLS];
@@ -494,7 +495,7 @@ static u64 __of_translate_address(struct device_node *dev,
 	bus = of_match_bus(parent);
 
 	/* Count address cells & copy address locally */
-	bus->count_cells(dev, &na, &ns);
+	bus->count_cells(dev, &na, &ns, flags);
 	if (!OF_CHECK_COUNTS(na, ns)) {
 		pr_debug("Bad cell count for %pOF\n", dev);
 		goto bail;
@@ -536,7 +537,7 @@ static u64 __of_translate_address(struct device_node *dev,
 
 		/* Get new parent bus and counts */
 		pbus = of_match_bus(parent);
-		pbus->count_cells(dev, &pna, &pns);
+		pbus->count_cells(dev, &pna, &pns, flags);
 		if (!OF_CHECK_COUNTS(pna, pns)) {
 			pr_err("Bad cell count for %pOF\n", dev);
 			break;
@@ -644,7 +645,7 @@ const __be32 *__of_get_address(struct device_node *dev, int index, int bar_no,
 		of_node_put(parent);
 		return NULL;
 	}
-	bus->count_cells(dev, &na, &ns);
+	bus->count_cells(dev, &na, &ns, false);
 	of_node_put(parent);
 	if (!OF_CHECK_ADDR_COUNT(na))
 		return NULL;
@@ -677,11 +678,15 @@ static int parser_init(struct of_pci_range_parser *parser,
 {
 	int rlen;
 
+	if (strcmp(name, "dma-ranges") == 0)
+		parser->flags = OF_CELLS_DMA;
+	else
+		parser->flags = 0;
+
 	parser->node = node;
-	parser->pna = of_n_addr_cells(node);
-	parser->na = of_bus_n_addr_cells(node);
-	parser->ns = of_bus_n_size_cells(node);
-	parser->dma = !strcmp(name, "dma-ranges");
+	parser->pna = of_addr_cells(node, parser->flags);
+	parser->na = of_bus_addr_cells(node, parser->flags);
+	parser->ns = of_bus_size_cells(node, parser->flags);
 	parser->bus = of_match_bus(node);
 
 	parser->range = of_get_property(node, name, &rlen);
@@ -730,7 +735,7 @@ struct of_pci_range *of_pci_range_parser_one(struct of_pci_range_parser *parser,
 
 	range->bus_addr = of_read_number(parser->range + busflag_na, na - busflag_na);
 
-	if (parser->dma)
+	if (parser->flags & OF_CELLS_DMA)
 		range->cpu_addr = of_translate_dma_address(parser->node,
 				parser->range + na);
 	else
@@ -747,7 +752,7 @@ struct of_pci_range *of_pci_range_parser_one(struct of_pci_range_parser *parser,
 
 		flags = parser->bus->get_flags(parser->range);
 		bus_addr = of_read_number(parser->range + busflag_na, na - busflag_na);
-		if (parser->dma)
+		if (parser->flags & OF_CELLS_DMA)
 			cpu_addr = of_translate_dma_address(parser->node,
 					parser->range + na);
 		else
diff --git a/drivers/of/base.c b/drivers/of/base.c
index d5a5c35eba72..39556fa7a13b 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -86,47 +86,89 @@ static bool __of_node_is_type(const struct device_node *np, const char *type)
 	return np && match && type && !strcmp(match, type);
 }
 
-int of_bus_n_addr_cells(struct device_node *np)
+int of_bus_addr_cells(struct device_node *np, unsigned int flags)
 {
+	struct device_node *parent;
 	u32 cells;
 
-	for (; np; np = np->parent)
+	while (np) {
+		if (flags & OF_CELLS_DMA)
+			if (!of_property_read_u32(np, "#dma-address-cells", &cells))
+				return cells;
+
 		if (!of_property_read_u32(np, "#address-cells", &cells))
 			return cells;
 
+		if (flags & OF_CELLS_DMA)
+			parent = __of_get_dma_parent(np);
+		else
+			parent = of_node_get(np->parent);
+
+		of_node_put(np);
+		np = parent;
+	}
+
 	/* No #address-cells property for the root node */
 	return OF_ROOT_NODE_ADDR_CELLS_DEFAULT;
 }
 
-int of_n_addr_cells(struct device_node *np)
+int of_addr_cells(struct device_node *np, unsigned int flags)
 {
-	if (np->parent)
-		np = np->parent;
+	int cells;
+
+	if (flags & OF_CELLS_DMA)
+		np = __of_get_dma_parent(np);
+	else if (np->parent)
+		np = of_node_get(np->parent);
+
+	cells = of_bus_addr_cells(np, flags);
 
-	return of_bus_n_addr_cells(np);
+	of_node_put(np);
+	return cells;
 }
-EXPORT_SYMBOL(of_n_addr_cells);
+EXPORT_SYMBOL(of_addr_cells);
 
-int of_bus_n_size_cells(struct device_node *np)
+int of_bus_size_cells(struct device_node *np, unsigned int flags)
 {
+	struct device_node *parent;
 	u32 cells;
 
-	for (; np; np = np->parent)
+	while (np) {
+		if (flags & OF_CELLS_DMA)
+			if (!of_property_read_u32(np, "#dma-size-cells", &cells))
+				return cells;
+
 		if (!of_property_read_u32(np, "#size-cells", &cells))
 			return cells;
 
+		if (flags & OF_CELLS_DMA)
+			parent = __of_get_dma_parent(np);
+		else
+			parent = of_node_get(np->parent);
+
+		of_node_put(np);
+		np = parent;
+	}
+
 	/* No #size-cells property for the root node */
 	return OF_ROOT_NODE_SIZE_CELLS_DEFAULT;
 }
 
-int of_n_size_cells(struct device_node *np)
+int of_size_cells(struct device_node *np, unsigned int flags)
 {
-	if (np->parent)
-		np = np->parent;
+	int cells;
+
+	if (flags & OF_CELLS_DMA)
+		np = __of_get_dma_parent(np);
+	else if (np->parent)
+		np = of_node_get(np->parent);
+
+	cells = of_bus_size_cells(np, flags);
 
-	return of_bus_n_size_cells(np);
+	of_node_put(np);
+	return cells;
 }
-EXPORT_SYMBOL(of_n_size_cells);
+EXPORT_SYMBOL(of_size_cells);
 
 #ifdef CONFIG_NUMA
 int __weak of_node_to_nid(struct device_node *np)
diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
index fb6792d381a6..f57900c3f25c 100644
--- a/drivers/of/of_private.h
+++ b/drivers/of/of_private.h
@@ -148,8 +148,18 @@ extern void __of_sysfs_remove_bin_file(struct device_node *np,
 #define for_each_transaction_entry_reverse(_oft, _te) \
 	list_for_each_entry_reverse(_te, &(_oft)->te_list, node)
 
-extern int of_bus_n_addr_cells(struct device_node *np);
-extern int of_bus_n_size_cells(struct device_node *np);
+extern int of_bus_addr_cells(struct device_node *np, unsigned int flags);
+extern int of_bus_size_cells(struct device_node *np, unsigned int flags);
+
+static inline int of_bus_n_addr_cells(struct device_node *np)
+{
+	return of_bus_addr_cells(np, 0);
+}
+
+static inline int of_bus_n_size_cells(struct device_node *np)
+{
+	return of_bus_size_cells(np, 0);
+}
 
 struct bus_dma_region;
 #if defined(CONFIG_OF_ADDRESS) && defined(CONFIG_HAS_DMA)
diff --git a/include/linux/of.h b/include/linux/of.h
index 8b9f94386dc3..dd4d4b3c8636 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -358,8 +358,21 @@ extern u64 of_get_cpu_hwid(struct device_node *cpun, unsigned int thread);
 #define for_each_property_of_node(dn, pp) \
 	for (pp = dn->properties; pp != NULL; pp = pp->next)
 
-extern int of_n_addr_cells(struct device_node *np);
-extern int of_n_size_cells(struct device_node *np);
+#define OF_CELLS_DMA 0x1
+
+extern int of_addr_cells(struct device_node *np, unsigned int flags);
+extern int of_size_cells(struct device_node *np, unsigned int flags);
+
+static inline int of_n_addr_cells(struct device_node *np)
+{
+	return of_addr_cells(np, 0);
+}
+
+static inline int of_n_size_cells(struct device_node *np)
+{
+	return of_size_cells(np, 0);
+}
+
 extern const struct of_device_id *of_match_node(
 	const struct of_device_id *matches, const struct device_node *node);
 extern int of_modalias_node(struct device_node *node, char *modalias, int len);
diff --git a/include/linux/of_address.h b/include/linux/of_address.h
index 265f26eeaf6b..15354085ea35 100644
--- a/include/linux/of_address.h
+++ b/include/linux/of_address.h
@@ -16,7 +16,7 @@ struct of_pci_range_parser {
 	int na;
 	int ns;
 	int pna;
-	bool dma;
+	unsigned int flags;
 };
 #define of_range_parser of_pci_range_parser
 
-- 
2.38.1

[PATCH v11 2/5] of: Introduce of_translate_dma_region()

[Thierry Reding]

From: Thierry Reding <treding@nvidia.com>

This function is similar to of_translate_dma_address() but also reads a
length in addition to an address from a device tree property.

Signed-off-by: Thierry Reding <treding@nvidia.com>
---
Changes in v11:
- updated to use #dma-{address,size}-cells

Changes in v10:
- new patch

 drivers/of/address.c       | 41 ++++++++++++++++++++++++++++++++++++++
 include/linux/of_address.h |  2 ++
 2 files changed, 43 insertions(+)

diff --git a/drivers/of/address.c b/drivers/of/address.c
index db59bc60226c..89b9f4fbad8f 100644
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -627,6 +627,47 @@ u64 of_translate_dma_address(struct device_node *dev, const __be32 *in_addr)
 }
 EXPORT_SYMBOL(of_translate_dma_address);
 
+/**
+ * of_translate_dma_region - Translate device tree address and size tuple
+ * @dev: device tree node for which to translate
+ * @prop: pointer into array of cells
+ * @start: return value for the start of the DMA range
+ * @length: return value for the length of the DMA range
+ *
+ * Returns a pointer to the cell immediately following the translated DMA region.
+ */
+const __be32 *of_translate_dma_region(struct device_node *dev, const __be32 *prop,
+				      phys_addr_t *start, size_t *length)
+{
+	struct device_node *parent;
+	u64 address, size;
+	int na, ns;
+
+	parent = __of_get_dma_parent(dev);
+	if (!parent)
+		return NULL;
+
+	na = of_bus_addr_cells(parent, OF_CELLS_DMA);
+	ns = of_bus_size_cells(parent, OF_CELLS_DMA);
+
+	of_node_put(parent);
+
+	address = of_translate_dma_address(dev, prop);
+	if (address == OF_BAD_ADDR)
+		return NULL;
+
+	size = of_read_number(prop + na, ns);
+
+	if (start)
+		*start = address;
+
+	if (length)
+		*length = size;
+
+	return prop + na + ns;
+}
+EXPORT_SYMBOL(of_translate_dma_region);
+
 const __be32 *__of_get_address(struct device_node *dev, int index, int bar_no,
 			       u64 *size, unsigned int *flags)
 {
diff --git a/include/linux/of_address.h b/include/linux/of_address.h
index 15354085ea35..a05c35b40295 100644
--- a/include/linux/of_address.h
+++ b/include/linux/of_address.h
@@ -38,6 +38,8 @@ struct of_pci_range {
 /* Translate a DMA address from device space to CPU space */
 extern u64 of_translate_dma_address(struct device_node *dev,
 				    const __be32 *in_addr);
+extern const __be32 *of_translate_dma_region(struct device_node *dev, const __be32 *addr,
+					     phys_addr_t *start, size_t *length);
 
 #ifdef CONFIG_OF_ADDRESS
 extern u64 of_translate_address(struct device_node *np, const __be32 *addr);
-- 
2.38.1

[PATCH v11 3/5] dt-bindings: reserved-memory: Document iommu-addresses

[Thierry Reding]

From: Thierry Reding <treding@nvidia.com>

This adds the "iommu-addresses" property to reserved-memory nodes, which
allow describing the interaction of memory regions with IOMMUs. Two use-
cases are supported:

  1. Static mappings can be described by pairing the "iommu-addresses"
     property with a "reg" property. This is mostly useful for adopting
     firmware-allocated buffers via identity mappings. One common use-
     case where this is required is if early firmware or bootloaders
     have set up a bootsplash framebuffer that a display controller is
     actively scanning out from during the operating system boot
     process.

  2. If an "iommu-addresses" property exists without a "reg" property,
     the reserved-memory node describes an IOVA reservation. Such memory
     regions are excluded from the IOVA space available to operating
     system drivers and can be used for regions that must not be used to
     map arbitrary buffers.

Each mapping or reservation is tied to a specific device via a phandle
to the device's device tree node. This allows a reserved-memory region
to be reused across multiple devices.

Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
---
Changes in v10:
- mark iommu-addresses as required in the absence of reg and size

Changes in v9:
- add Reviewed-by tags

Changes in v8:
- include validation warnings that had crept into an unrelated patch

Changes in v7:
- keep reserved-memory.txt to avoid broken references

Changes in v6:
- add device phandle to iommu-addresses property in examples
- remove now unused dt-bindings/reserved-memory.h header

 .../reserved-memory/reserved-memory.yaml      | 73 +++++++++++++++++++
 1 file changed, 73 insertions(+)

diff --git a/Documentation/devicetree/bindings/reserved-memory/reserved-memory.yaml b/Documentation/devicetree/bindings/reserved-memory/reserved-memory.yaml
index 44f72bcf1782..07711fb30518 100644
--- a/Documentation/devicetree/bindings/reserved-memory/reserved-memory.yaml
+++ b/Documentation/devicetree/bindings/reserved-memory/reserved-memory.yaml
@@ -52,6 +52,30 @@ properties:
       Address and Length pairs. Specifies regions of memory that are
       acceptable to allocate from.
 
+  iommu-addresses:
+    $ref: /schemas/types.yaml#/definitions/phandle-array
+    description: >
+      A list of phandle and specifier pairs that describe static IO virtual
+      address space mappings and carveouts associated with a given reserved
+      memory region. The phandle in the first cell refers to the device for
+      which the mapping or carveout is to be created.
+
+      The specifier consists of an address/size pair and denotes the IO
+      virtual address range of the region for the given device. The exact
+      format depends on the values of the "#address-cells" and "#size-cells"
+      properties of the device referenced via the phandle.
+
+      When used in combination with a "reg" property, an IOVA mapping is to
+      be established for this memory region. One example where this can be
+      useful is to create an identity mapping for physical memory that the
+      firmware has configured some hardware to access (such as a bootsplash
+      framebuffer).
+
+      If no "reg" property is specified, the "iommu-addresses" property
+      defines carveout regions in the IOVA space for the given device. This
+      can be useful if a certain memory region should not be mapped through
+      the IOMMU.
+
   no-map:
     type: boolean
     description: >
@@ -95,6 +119,55 @@ oneOf:
   - required:
       - size
 
+  - required:
+      - iommu-addresses
+
 additionalProperties: true
 
+examples:
+  - |
+    / {
+      compatible = "foo";
+      model = "foo";
+
+      #address-cells = <2>;
+      #size-cells = <2>;
+
+      reserved-memory {
+        #address-cells = <2>;
+        #size-cells = <2>;
+        ranges;
+
+        adsp_resv: reservation-adsp {
+          /*
+           * Restrict IOVA mappings for ADSP buffers to the 512 MiB region
+           * from 0x40000000 - 0x5fffffff. Anything outside is reserved by
+           * the ADSP for I/O memory and private memory allocations.
+           */
+          iommu-addresses = <&adsp 0x0 0x00000000 0x00 0x40000000>,
+                            <&adsp 0x0 0x60000000 0xff 0xa0000000>;
+        };
+
+        fb: framebuffer@90000000 {
+          reg = <0x0 0x90000000 0x0 0x00800000>;
+          iommu-addresses = <&dc0 0x0 0x90000000 0x0 0x00800000>;
+        };
+      };
+
+      bus@0 {
+        #address-cells = <1>;
+        #size-cells = <1>;
+        ranges = <0x0 0x0 0x0 0x40000000>;
+
+        adsp: adsp@2990000 {
+          reg = <0x2990000 0x2000>;
+          memory-region = <&adsp_resv>;
+        };
+
+        dc0: display@15200000 {
+          reg = <0x15200000 0x10000>;
+          memory-region = <&fb>;
+        };
+      };
+    };
 ...
-- 
2.38.1

[PATCH v11 4/5] iommu: Implement of_iommu_get_resv_regions()

[Thierry Reding]

From: Thierry Reding <treding@nvidia.com>

This is an implementation that IOMMU drivers can use to obtain reserved
memory regions from a device tree node. It uses the reserved-memory DT
bindings to find the regions associated with a given device. If these
regions are marked accordingly, identity mappings will be created for
them in the IOMMU domain that the devices will be attached to.

Cc: Frank Rowand <frowand.list@gmail.com>
Cc: devicetree@vger.kernel.org
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>
---
Changes in v10:
- extract more code into the new iommu_resv_region_get_type() function
- rename variables for physical and I/O virtual addresses for clarity
- default to IOMMU_RESV_DIRECT instead of IOMMU_RESV_DIRECT_RELAXABLE
- use newly introduced of_translate_dma_region()

Changes in v9:
- address review comments by Robin Murphy:
  - warn about non-direct mappings since they are not supported yet
  - cleanup code to require less indentation
  - narrow scope of variables

Changes in v8:
- cleanup set-but-unused variables

Changes in v6:
- remove reference to now unused dt-bindings/reserved-memory.h include

Changes in v5:
- update for new "iommu-addresses" device tree bindings

Changes in v4:
- fix build failure on !CONFIG_OF_ADDRESS

Changes in v3:
- change "active" property to identity mapping flag that is part of the
  memory region specifier (as defined by #memory-region-cells) to allow
  per-reference flags to be used

Changes in v2:
- use "active" property to determine whether direct mappings are needed

 drivers/iommu/of_iommu.c | 94 ++++++++++++++++++++++++++++++++++++++++
 include/linux/of_iommu.h |  8 ++++
 2 files changed, 102 insertions(+)

diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
index 5696314ae69e..fa7c63a4abbf 100644
--- a/drivers/iommu/of_iommu.c
+++ b/drivers/iommu/of_iommu.c
@@ -11,6 +11,7 @@
 #include <linux/module.h>
 #include <linux/msi.h>
 #include <linux/of.h>
+#include <linux/of_address.h>
 #include <linux/of_iommu.h>
 #include <linux/of_pci.h>
 #include <linux/pci.h>
@@ -172,3 +173,96 @@ const struct iommu_ops *of_iommu_configure(struct device *dev,
 
 	return ops;
 }
+
+static enum iommu_resv_type iommu_resv_region_get_type(struct device *dev, struct resource *phys,
+						       phys_addr_t start, size_t length)
+{
+	phys_addr_t end = start + length - 1;
+
+	/*
+	 * IOMMU regions without an associated physical region cannot be
+	 * mapped and are simply reservations.
+	 */
+	if (phys->start >= phys->end)
+		return IOMMU_RESV_RESERVED;
+
+	/* may be IOMMU_RESV_DIRECT_RELAXABLE for certain cases */
+	if (start == phys->start && end == phys->end)
+		return IOMMU_RESV_DIRECT;
+
+	dev_warn(dev, "treating non-direct mapping [%pr] -> [%pap-%pap] as reservation\n", &phys,
+		 &start, &end);
+	return IOMMU_RESV_RESERVED;
+}
+
+/**
+ * of_iommu_get_resv_regions - reserved region driver helper for device tree
+ * @dev: device for which to get reserved regions
+ * @list: reserved region list
+ *
+ * IOMMU drivers can use this to implement their .get_resv_regions() callback
+ * for memory regions attached to a device tree node. See the reserved-memory
+ * device tree bindings on how to use these:
+ *
+ *   Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt
+ */
+void of_iommu_get_resv_regions(struct device *dev, struct list_head *list)
+{
+#if IS_ENABLED(CONFIG_OF_ADDRESS)
+	struct of_phandle_iterator it;
+	int err;
+
+	of_for_each_phandle(&it, err, dev->of_node, "memory-region", NULL, 0) {
+		const __be32 *maps, *end;
+		struct resource phys;
+		int size;
+
+		memset(&phys, 0, sizeof(phys));
+
+		/*
+		 * The "reg" property is optional and can be omitted by reserved-memory regions
+		 * that represent reservations in the IOVA space, which are regions that should
+		 * not be mapped.
+		 */
+		if (of_find_property(it.node, "reg", NULL)) {
+			err = of_address_to_resource(it.node, 0, &phys);
+			if (err < 0) {
+				dev_err(dev, "failed to parse memory region %pOF: %d\n",
+					it.node, err);
+				continue;
+			}
+		}
+
+		maps = of_get_property(it.node, "iommu-addresses", &size);
+		if (!maps)
+			continue;
+
+		end = maps + size / sizeof(__be32);
+
+		while (maps < end) {
+			struct device_node *np;
+			u32 phandle;
+
+			phandle = be32_to_cpup(maps++);
+			np = of_find_node_by_phandle(phandle);
+
+			if (np == dev->of_node) {
+				int prot = IOMMU_READ | IOMMU_WRITE;
+				struct iommu_resv_region *region;
+				enum iommu_resv_type type;
+				phys_addr_t iova;
+				size_t length;
+
+				maps = of_translate_dma_region(np, maps, &iova, &length);
+				type = iommu_resv_region_get_type(dev, &phys, iova, length);
+
+				region = iommu_alloc_resv_region(iova, length, prot, type,
+								 GFP_KERNEL);
+				if (region)
+					list_add_tail(&region->list, list);
+			}
+		}
+	}
+#endif
+}
+EXPORT_SYMBOL(of_iommu_get_resv_regions);
diff --git a/include/linux/of_iommu.h b/include/linux/of_iommu.h
index 55c1eb300a86..9a5e6b410dd2 100644
--- a/include/linux/of_iommu.h
+++ b/include/linux/of_iommu.h
@@ -12,6 +12,9 @@ extern const struct iommu_ops *of_iommu_configure(struct device *dev,
 					struct device_node *master_np,
 					const u32 *id);
 
+extern void of_iommu_get_resv_regions(struct device *dev,
+				      struct list_head *list);
+
 #else
 
 static inline const struct iommu_ops *of_iommu_configure(struct device *dev,
@@ -21,6 +24,11 @@ static inline const struct iommu_ops *of_iommu_configure(struct device *dev,
 	return NULL;
 }
 
+static inline void of_iommu_get_resv_regions(struct device *dev,
+					     struct list_head *list)
+{
+}
+
 #endif	/* CONFIG_OF_IOMMU */
 
 #endif /* __OF_IOMMU_H */
-- 
2.38.1

[PATCH v11 5/5] iommu: dma: Use of_iommu_get_resv_regions()

[Thierry Reding]

From: Thierry Reding <treding@nvidia.com>

For device tree nodes, use the standard of_iommu_get_resv_regions()
implementation to obtain the reserved memory regions associated with a
device.

Cc: Rob Herring <robh+dt@kernel.org>
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: devicetree@vger.kernel.org
Signed-off-by: Thierry Reding <treding@nvidia.com>
---
 drivers/iommu/dma-iommu.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 9297b741f5e8..709b05d3aad2 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -23,6 +23,7 @@
 #include <linux/memremap.h>
 #include <linux/mm.h>
 #include <linux/mutex.h>
+#include <linux/of_iommu.h>
 #include <linux/pci.h>
 #include <linux/scatterlist.h>
 #include <linux/spinlock.h>
@@ -391,6 +392,8 @@ void iommu_dma_get_resv_regions(struct device *dev, struct list_head *list)
 	if (!is_of_node(dev_iommu_fwspec_get(dev)->iommu_fwnode))
 		iort_iommu_get_resv_regions(dev, list);
 
+	if (dev->of_node)
+		of_iommu_get_resv_regions(dev, list);
 }
 EXPORT_SYMBOL(iommu_dma_get_resv_regions);
 
-- 
2.38.1

Re: [PATCH v11 0/5] iommu: Support mappings/reservations in reserved-memory regions

[Joerg Roedel]

On Fri, Nov 11, 2022 at 05:18:01PM +0100, Thierry Reding wrote:
> Thierry Reding (5):
>   of: Introduce support for #dma-{address,size}-cells
>   of: Introduce of_translate_dma_region()
>   dt-bindings: reserved-memory: Document iommu-addresses
>   iommu: Implement of_iommu_get_resv_regions()
>   iommu: dma: Use of_iommu_get_resv_regions()
> 
>  .../reserved-memory/reserved-memory.yaml      | 73 ++++++++++++++
>  drivers/iommu/dma-iommu.c                     |  3 +
>  drivers/iommu/of_iommu.c                      | 94 +++++++++++++++++++
>  drivers/of/address.c                          | 84 +++++++++++++----
>  drivers/of/base.c                             | 70 +++++++++++---
>  drivers/of/of_private.h                       | 14 ++-
>  include/linux/of.h                            | 17 +++-
>  include/linux/of_address.h                    |  4 +-
>  include/linux/of_iommu.h                      |  8 ++
>  9 files changed, 329 insertions(+), 38 deletions(-)

Despite this lacking some essential reviews, what is the plan with this
code? Should it go through the IOMMU or DT tree?

Regards,

	Joerg